This invention relates generally to printed paper and to a method and apparatus of the type used to print on and emboss a print media so as to simulate engraved printing and more particularly to a method and apparatus for repetitive printing with simulated engraving on a continuously moving web of print media of extended length. With word processing and computer controlled printers making ever-increasing inroads on office procedures for production of printed pages, a conflict arises between the desire of many firms to use high quality stationery in a format including engraved letterheads and the desire to take advantage of the high speed capability of said computer and word processor controlled printers. Such printers are typically fed with paper in the form of a fan-folded continuous web where perforated lines separate consecutive sheets of paper, and sprocket holes are provided on perforated strips outside the conventional margins of the finished printed page for advancing the paper.
To provide such fanfolded webs with preprinted letterheads on every web segment does not present great difficulties. However, it has heretofore not been possible to provide continuous webs of paper having preprinted letterheads which are engraved. Many large and small corporations, law firms, professional people, and the like, require that all company correspondence be on letterhead paper wherein the characters of the letterhead are engraved or at least raised above the paper.
Engraving is a process which is costly and time consuming because each sheet is printed individually. In the well known method, plates are prepared engraved with the characters which are to appear in raised ink on the finished product. The engraved grooves are filled with ink. Excess ink is removed and the sheet to be printed is pressed between the ink filled plate and a backing plate such that the ink from the engraved grooves attaches to the paper. Such a process is not novel. Therefore further description is not included herein. The finished product, using a letterhead as an example, is a sheet of paper having a printed letterhead wherein all letters are raised by the ink thickness above the general planar level of the paper. Additionally, on the reverse side of the paper there are depressions corresponding to each letter which has been printed in engraved format, which depressions result from the high pressure used in pressing the paper against the grooves in the ink filled engraving plate in order to cause the ink to transfer from the plate to the paper.
Thus, a cursory examination of a firm's stationery to ascertain whether engraving has been used on the letterhead involves the steps, consciously or subconsciously, of running one's finger over the print to see whether the ink is raised and running a finger behind the print or inspecting the backside of the paper to see whether a depression exists corresponding with the outlines of the raised ink letters on the opposite face of the paper.
In another less expensive technique for producing letterheads of good quality which resemble engraved printing, the paper is printed and while the ink is wet or moist the characters are powdered with an adhering resin powder or similar material adapted to fuse and set after application of heat. The application of heat causes melting of the resinous compound whereby the particles fuse together on the ink and harden. The fused particles produce a generally raised effect for the characters. This process is known as thermography. As stated, it has the advantage of producing raised ink characters without the expensive sheet by sheet pressing used in the engraving technique. However, although the letters are raised on the front face of the paper, the reverse side of the paper has no impression. Therefore it is no problem for those interested in such matters to determine that the paper and letterhead are in fact not engraved. As stated, for many users, for example, large law firms, such "less-than-the-best" quality is unacceptable.
What is needed is a simple and effective method and apparatus for simulating engraved paper which can be accomplished in a continuous high speed process on a continuous web of paper.